RE: Formations/groups

From: Anthony J. Kroes (
Date: Mon Jul 14 2003 - 13:20:20 EDT

  • Next message: Kevin Fetter: "Re: Formations/groups"

    Thanks to those who responded to my 'formations' question.  Unfortunately,
    not being familiar with many of the terms you folks use here (so far I just
    look at the sky and watch them) I have even more questions now!
    First, is there a FAQ or other good resource about general terms and info
    about orbits and tracking?
    1.  What is 'OIG' ?
    2.  I see a lot of rows of numbers posted on these messages.  Assuming they
    are orbital elements, why are there 2 different formats, what is the
    difference between them, and what does the information do for me (or anyone
    else reading it), and how do I use that info?
    3.  What are orbital 'planes'?
    4. When you say "52 Globalstar satellites at 52 degrees", what does that
    mean?  Is there a correspondence with the number of satellites and the
    orbits?  Are they all at '52 degrees'?  What is that measured from - the
    ground, azimuth, etc?
    I see a lot of good info here, but being new and jumping in with both feet,
    I can't use most of it yet.
    Anthony J. Kroes
    Cedar Drive Observatory
    Pulaski, WI
    -----Original Message-----
    From: Björn Gimle [] 
    Sent: Monday, July 14, 2003 2:24 AM
    To:;; Tony Beresford
    Subject: Re: Formations/groups
    > >Recently my interest has turned to watching 'formations' of sats  
    > >(i.e. 2 or more sats traveling together).  I am aware of, and  have 
    > >viewed, the NOSS triplets on a number of occasions, and  have also 
    > >seen the Grace 1 & 2 sats. Are there any other sats up there that 
    > >travel together on a  regular basis?
    > There are about 52 Globalstar satellites at 52 degrees, and some 86 
    > Iridium satellites flying at 86 degrees, in formation.
    > Among the OIG published satellites the only grouping of any size is 
    > the Cluster "constellation" comprising 4 ESA built, Russian launched 
    > satellites studying the magnetosphere.
    The Globalstars are 6 satellites in 8 planes, that maintain a 19 minute
    separation within the plane. The remaining 4 satellites are out-of-plane and
    with varying orbital periods.
    The Iridiums are 11 satellites in 6 planes, and of the remaining 24, 7 are
    known to tumble, 17 are "operational spares", most of them 100 km or less
    below the operational ones, but controlled to maintain the orbit plane. Thus
    each day several satellites will overtake some others in some plane(s), and
    then appear to fly together.
    There are also a few Cosmos satellites (like 2333) close to their Zenith-2
    rockets, that can appear together for several days at long intervals. Also
    25730 Feng Yun 1C/25731 Shi Jian 5 (spring 2004), and the 20792/20793 Atm
    canisters, but that will not be in a VERY long time.
    And do make an effort to see the Japanese IGS 2 to be launched in September!
    The IGS 1 objects were a spectacular group the first few days after launch,
    but it was only visible at my northern latitude at that time.
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